Com-pahy



G. R. MCDONALD Feb. 3, 1931. REGULATING SYSTEM Re. 17,953

Original Filed Feb. 5, 1926 w W Fig.1. I I

3 L-zz IHWQW /7 L75 2 Inventor:

GOTdOh R-M Donald;

H is Abbornes.-

Reissued Feb. 3, 1931 GORDON R. MODQNALD, or ERIE, PENNSYLVANIA, AssIGNon'ro GENERAL ELECTRIC COMPANY, A con-rename or NEW YORK REGULATING SYSTEM Original No. 1,693,307, dated November 27, 1928, Serial No. 86,329, filed February 5,- 1926 .Application for rcissue filed February 12, 1930. Serial No. 42?,917.

My invention relates to regulating systems for maintaining a predetermined division of load between a plurality of parallelmachines and itsobject is to provide an improved system for accomplishing this result.

My invention is especially applicable to a regulating system for maintaining the load properly divided between a plurality of overcompound direct current generators connected to a common network.

My invention will be better understood from the following description taken in connection withthe accompanying drawing, and its scope will be pointed out in the appended claims. 1 In the accompanying drawing, which shows my invention in connection with a load regulating system for two overcompound di rect current generators connected in parallel, Fig. 1 shows one embodiment of my inven tion and Fig. 2 shows a modification of the embodiment shown in Fig. 1.

Referring to Fig. 1, 1 and 2 are two overcompound direct current generators which are respectively connected to the direct current net work 3 by suitable switching means 4 and 5. These switching means may be of any, suitable type and may be controlled either manually or automatically. For example, each means may form a part of an automatic switching equipment, examples of which are well known in the art, whereby it is closed automatically after the respective generator has been started and has reached a predetermined condition.

Each generator is provided with the usual series, commutating, and shunt field windings. As shown in the drawings, 7 and 8 are the series field windings, 9 and 10 are the commutating field windings, and 11 and 12 are the shunt field windings of the generators 1 and 2 respectively. a

13 represents any suitable switching means which, when closed, completes an equalizing connection between the two series field windings so that substantially equal currents flow through the series field windings; It is preferable in some cases to complete this connection only after both machines are connected in parallel. Therefore, I have shown the cirtion;

cuit of the closing coil of the switch 13 as including auxiliary contacts on the switches tomatically controlled, to open. and close the circuit of the closing coil of the switch 13 at'the proper time.

For equalizing the loads on the two 'genera tors, suitable current limiting means, shown as resistors 15 and 16, are respectively provided in the circuits of the field windings 11 and 12, and a polarized relay 17 of any suitable type, examples of which are well known in the art, is provided for selectively controlling a short circuit around each resistor in accordance with the relative current outputs of the two generators. For the purpose of this invention, a polarized relay is defined as a relay which has a movable member, the position of which depends upon the relative directions of two magnetic fields, the direction of one of the fields being substantially constant while the direction of the other field is variable.

As shown in the drawing, the polarized relay 17 comprises an armature 18 pivotally mounted within the two windings 19 and 20 which are therefore in mutual inductive rela- The mutually inductive windings 19 and 20 are wound differentially with respect to each other and are respectively connected so as to be energized in accordance with the current outputs of the generatorsl and 2. As shown in thedrawing, the winding 19 is connccted in parallel with the commutating winding 9 and the winding 20 is connected in parallel with the commutating winding 10. The armature 18 also is pivoted between the polar projections of a stationary magnetic member 21 so that the armature occupies different positions-depending upon the direction and magnitude of the resultant magnetoino turns of the winding19 exceed the ampere turns of thewin ding by a predetermined amount, the direction and amount of flux in armature 18 is such that the armature is.

moved to the right and connects the contacts 22 togethen thereby completing a short cirmore quickly. v ,lVhen thesecon'd machine is connectedto': the network'73- and the auxiliary contacts cuit around the resistor 16. When the ampere turns of the winding 1 9v are less than the ampere turns of the windin -5 20 by a prede 'termined amount, the direction and amount of flux in the armature 18 is such that the armature is moved to the left and connects the contacts 23 together,-there,by completing a short circuit around the resistor 15. The windings 19and20 are designed so that their ampere turns aresubstantially equal when the load is divided in the desired manner between the two machines. 7

The magnetic member 21 may be a perma- "nent magnet but preferably it is magnetized by meansof a magnetizing winding 25, the

., circuit of which" is arranged to be completed across a suitable source of direct current of a definite polarity, such as the network 3.

Suitable adjustable rheostats 281and 29 may be provided in the circuits of the shunt field windings 11 and 12 respectivejly, whereby the voltage of the generators may be regulated. The adjustments of these rheostats may be controlled either manually'or automatically in a manner well known in the art.

The operation of the system shown in Fig. 1 is as follows: hen only one generator is in operation, the switch 13 is open so that the the current winding 19 and the windingf25' ofthe relay 17 are energized. The energization of'the current winding 19, under such conditions, causes the relay 17 to close its contacts 22 and thereby short circuit the resistor 16 in the circuit ofthe field winding 12 of generator 2. Since the generator'2 is not connected'to the network, the short circuiting of the resistor 16'has 'no' effect atthis time,

but when the generator 2 is being started the fact that the resistor 16 is short eircuited causes the machine to build "30 'aIid31 on' the circuit breakers 4 and 5 complete .the circuit of the closing coil ofthe switch 13, the relay 17 then operates to control thedivision of the load between up itsvoltage the two machines. If the current output of the generator 1 is too great relatively to the current output of the generator 2,

the relay 17 closes its contacts 22, thereby iincreasing thei excitation of the generator 2. This increase in-the excitation of the generator 2 increases its current output tively to the output of the generator 1, the re- -la yr17 thenoperates to ope'nits contacts 22 [which remain open until the output of the generator. 2 again decreases relatively to the output of the generator 1. If the current outrelay 17 closes its, contacts 23 to effect an increase in the excitation 'ofthe generator 2 until desired current balance is restored when the relay 17 opens its contacts 23.

Tests have shown that by means of my improved arrangement'it is possible to operate in parallel two overcompound direct cur-.

put of the generator 2 is too great relatively to thecurrent output of the generator. 1, the

rent generators which have materially different volt-ampere characteristics and maintain the load divided between the two machines in the desired manner for all values of load.

It willbe obvious to those skilled in the-art that my invention has the inherent advantage wound machine, when converted in parallel j" with a-hot'machine, tends to maintain a higher terminal voltage than the hot machine and consequently the cold machine tends to carry more than its share of the total'load; The re I lay 17 operates under such conditions to conmachine supplying current towthe network,"

trol the short circuiting of theresistorin the shuntlfield circuit o'fthe hot machine to maintam the voltages of the two parallel connected machines equal and keeps the desired division of current between them. If a cold machine placed in operation ata time when the load is such that the higher voltage. of the cold machine causesthe current through the'jhot .machine to-reverse, the direction of the circulatin gcurrent between:the two machines is such thatthe torque produced bythe reverse currentthrough the relay current winding associated with the hot machine is in a direction; tocause therelay 17 to short circuit the resistor in the field circuit of the hot machine, Therefore, under such reverse current conditions, the currents in both of the current windings 19 and 20 of the relay 17 produce torquesin 'the same direction to cause the relay to short circuit the resistor in the field circuit of the hot machine.

While I have described the arrangement shown in this figure as controlling the outputs of two machines 1 and 2 so as to 1111111- tain a predetermined division between t e outputs thereof, this arrangement is also arranged to maintain the desired relation between the current supplied to the two ma chines when they receive current from the load circuit. For example, assume the two machines 1 and 2 are connected to the circuit 3 and are receiving current therefrom and the current supplied to the machine 1 is greater than the current supplied to the machine 2. Under these conditions the ampere turns of the winding 19 of the polarized relay 17 exceed the ampere turns of the winding 20. Since, however, the current through these windings are in the opposite directions from what they are when the machines 1 and 2 are supplying current to the load circuit, the resultant flux produced in the armature 18 of the polarized relay 17 is also in the opposite direction. Therefore, the relay l7 operates to close its contacts 23 instead of its contacts 22. The closing of the contacts 23 eiiects in the manner heretofore described an increase in the excitation of the machine 1 so that the amount of current supplied to the machine 1 is decreased.

In a similar manner, if the current supplied to the machine 2 exceeds the amount of current supplied to the machine 1, the polarized relay 17 operates to close its contacts 22 and effects an increase in the excita tion of the machine 2 so as to decrease the amount of current supplied thereto. 7

The relay 17,therefore, operates to maintain the proper division of current between the two machines whether the machines are supplying current to the load circuit or receiving current from the load circuit.

In the modification of Fig. 1 shown in Fig. 2, the two current coils 19 and 20 of the regulating relay 17 are connected in series in the equalizer connection. It will be observed that by means of such a connection the direction and magnitude of the flux in the armature 18 varies in accordance with the relative current output of the two machines in the same manner as in Fig. 1. When the generator 1. is supplying more than its share of theload, the voltage drop across the series field winding 7 is greater than the voltage drop across the field winding 8. Therefore, current flows through the equalizer connections and the current coils 19 and 20 from the field winding 7 to the field winding 8. The direction of the current through the current coils 19 and 2.0 under these conditions is such as to cause the relay 17 to close its contacts 22, thereby cfiecting an increase in the current output of the generator 2 to restore the proper division of the load between the two generators.

When the generator 2 is supplying more than its share of the load, the voltage drop across the series field winding 7 is less than the voltage drop across the series field winding 8..

Consequently, current flows through the equalizer connection and the current coils 19 and 20 in the opposite direction so that the relay 17 closes its contacts 23, thereby efiec-ting an increase in tie current output of the generator 1 to restore the proper division. of the load between the two generators. The arrangement shown in 2 is also arranged to maintain the proper division between the currents through the machines 1 and 2 when they receive current from the load circuit 3. For example, if the current supplied to the machine 1 exceeds the current supplied to the machine 2 the polarized relay 17 operates to close its contacts 28 instead of its contacts 22 since the voltage drop across the inding 7 while greater than the voltage drop across the winding 8, is in the opposite direction from what it is when the machine 1 is supplying the greater current to the load circuit. Consequently, the current through the windings 19 and 20 of the relay 17 is also in the opposite direction so that the flux produced in the armature of the polarized relay 17 is in a direction to cause the relay to close its contacts 23. The closing of the contacts eiiects an increase inthe excitation of the machine 1. In a similar manner the relay 17 operates to close its cont-acts 22 to eiiect an increase in the excitation of the machine 2 when the current supplied to the machine 2 exceeds the amount supplied to the machine 1.

While I have in accordance with the patent statutes shown and described my invention as applied to a particular system and as embodying various devices diagrammatically indicated, changes and modifications will be obvious to those skilled in the art, andI there fore aim in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is,

1. In a regulating system, two direct current generators connected in parallel, a field circuit for each generator, current limiting means in each field circuit, and a polarized relay connected and arranged so that when the current output of one of generators is too great relatively to the current output of the other generator, said polarized relay occupies a position to decrease the amount of current limiting means in the field circuit of said other generator and when the current output of said one of said generators is too small relatively to the current output of said other generator, said polarized relay occupies a position to decrease the amount of current limiting means in the field circuit of said one of said generators.

2. In a regulatingsystem, two generators Bil connected in parallel, and a polarized relay for controlling theexcitation of one'of said generators, comprising two mutually inductives difi'erentially wound windings respec: tively. energized in accordance with the current outputs of the two generators.

3. In a regulating system, two direct current generators connected in parallel, each generator being provided with a series connected field winding, and a polarized relay for controllingthe excitation of one of said generators comprising a magnetic member and two differentially wound windings around said member respectively connected in parallel with said series connected field windings.

4. In combination, two dynamoelectric machines connected in parallel, a polarized relay arranged when in .one position to effect a change in the excitation of one of said ma chines and when in another position to effect a change in the excitation of-the other of said'machines and means for producing a magnetomotive force in said relay which varies in direction andmagnitude in accordance with the difierence between the loads of the two machines whereby said relay'is moved into one'of said positions when the load on one of said machines exceeds the load on the other and is moved into the other of said positions when the load on said one of said machines is less than the load on the other.

5. In a load regulating system for two direct current generators connected in parallel, a polarized relay arr nged when in one position to effect a change in the excitation of one of the generators and when in another position to effect a change in the excitation of the v I other generator, and means for producing a magnetomotive force in said relay which varice in direction and magnitude in accordance with the difference between thecurrent outputs of the two generators comprising two differentially wound windings for said relay arranged so that when the ampere turns of one of said windings exceeds the ampere turns of the other winding, said relay is moved into one of said positions, and when the ampere turns of said one of said windings is less than the ampere turns of the other winding said relay is moved into the other of said positions, one of said windings being connected so that his energized in accordance with the current output of one of said generators and the other of said'windings being connected so that it is energized in accordance with the current outputof the other generator.

' 6. In a load regulating system for two overcompound direct'current generators connected in parallel, the combination of a resistor inthe shunt field circuit of each generator, a

V polarizedrelay arranged when in one position to effect the short circuiting of one of sai'd'resistors and when in another position to effect the short OlI'QUltlIlgOf the other resistor, and means'for producing a magnetomotive force in said relay which varies in direction and magnitude in accordance withthe difierence between the current outputs of the two generators, whereby said relay is moved to one of said positions when the current output of a predetermined one of said generators exceeds the current output of the other generator and is moved to the other position when the current output of said predetermined one or" said generators is less than the current output of the other generator.

7. In a load regulating system for two compound direct current generators connected in parallel, the combination of a resistor in the shunt field circuit of each generator, and a polarized relay arranged when in one position to effect the short circuiting of one of said resistors and when in another position to effect the short circuiting of the other resister, said relay having two differentially wound windings respectively connected in parallel with the series connected field windings of the two generators whereby said relay is moved to one of said positions when the current output of a predetermined one of said generators exceeds the other by a predetermined amount and said relay is moved to the other of said positions when the current output of said predetermined one of said generators is less than the other by a predetermined amount.

8. In a regulating system, two overcompound' direct current generators connected in parallel, current limiting means in the field circuit of each generator, and a polarized relay controlled by the relative current outputs of the two generators for selectively short circuiting the current limiting means in the field circuit of the generator furnishing the smaller current.

9. In a load regulating system for two dynamoelectric machines operating in parallel, the combination of current limiting means in the field circuit of one of said machines,and a polarized relay for varying the amount of said current limiting means in said .field circuit comprising means for producing a main magnetomotive force, a magnetic member and means for producing in said magnetic member an auxiliary magnetomotive force whose direction and magnitude vary directly with the difference between the outputs of the machines, said magnetomotive forces and said magnetic member cooperating to cause said relay to effect a 'decrease'in the amount. of current limiting means in the field circuit only when the output of the other machine exceeds the output of said one of said machines.

10. In a load regulating system for two dynamoelectric machines operating in parallel, the combination of current limiting means in the field circuit of one of said machines, and means for varying the amount when the output of the other machine exceedsthe output of said one of said machines.

11. In a regulating system, two dynamoelectric machines connected in parallel, and means for regulating the relative currents flowing through the two machines including a polarized relay responsive to the direction and relative magnitudes of the currents flowing through the two machines for controlling the current through one of said machines.

12. In a regulating'system, an electric circuit, two dynamoelectric machines connected in parallel across said circuit and a polarized relay responsive to the direction and relative magnitudes of the currents flowing through r the two machines for efiecting a predetermined change in the current through one of the machines when it is supplying to said circuit a greater current than the other machine is supplying and a similar change when said one of said machines is receiving from said circuit a smaller current than the other machine is receiving.

13. In a regulating system, two dynamoelectric machines connected in parallel, and a polarized relay for controlling the excitation of one of said machines to maintain a predetermined relation between the currents flowing through said machines comprising two mutually inductive difi erentially wound windings respectively energized in accordance with the currents flowing through the two machines.

14. In an automatic station, means for con trolling the voltage of a machine connected in parallel with another machine to control the relative currents through the machines including a polarized relay having a winding energized in accordance with the magnitude and direction of the current through one of said machines, and resistance shunting means controlled thereby.

15. In combination a plurality of translating devices adapted to be connected in parallel, and means for controlling the voltage of one of said devices including a polarized relay having a winding energized in accordance with the magnitude and direction of the current through one of said devices and resistance shunting means controlled thereby.

16. Means for controlling the relative currents between translating devices connected in parallel comprising means including a polarized relay having a winding connected in series relation with one of said devices for controlling the voltage of one of said devices whereby the said voltage is equalized with that of the other device.

17. In a regulating system, a plurality of translating devices connected in parallel, and means including a polarized relay having a winding connected in series relation with one of said devices for controlling the voltage of one of said devices to control the relative currents through said devices.

18. In combination, a plurality of sources of current, means for connecting said sources in parallel, and means for controlling the relative currents through said devices when said sources are connected in parallel comprising a polarized relay having a winding energized in accordance with the magnitude and direction of the current through one of said sources for varying the excitation of one of said sources.

19. In combination with a plurality of sources of current and a field rheostat associated with each source, or" means for equalizing the voltage of one of the sources with that of another source to control the relative currents through them including a polarized relay having a winding energized in accordance with the magnitude and direction of current through one of said sources and means controlled by said relay for short-circuiting a portion of the field rheostat of one of said sources whereby its excitation is increased to equalize its terminal voltage with that of the other source. I

20. In an automatic station, a plurality of translating units, each unit having a shunt field circuit, means for controlling the relative currents through said units when connected in parallel including a'polarized relay energized in accordance with the magnitude and direction of the current through one of said sources and means controlled thereby for varying the resistance of the shunt field circuit of one of the units to equalize its voltage with that of the other unit.

In witness whereof, I have hereunto set my hand this 7th day of February, 1930.

GORDON R. MGDONALD. 

